Colombia's army said Wednesday 10 of its soldiers were killed and 20 injured in an apparent attack by rebels that could jeopardize ongoing peace negotiations. The army's third division said in a statement that the soldiers were on a routine patrol in the volatile southwestern region of Cauca when they were ambushed around midnight Tuesday by a guerrilla unit of the Revolutionary Armed Forces of Colombia (FARC). "This is precisely why we want to end the war," President Juan Manuel Santos said in a statement. In December, FARC negotiators pledged to observe a unilateral cease-fire to promote peace talks being held in Cuba. The Bogota government responded by suspending all aerial attacks on rebel bases.